Recently, three-dimensional display devices displaying an image signal three-dimensionally have been widely used. Each pixel of a three-dimensional image has depth information in addition to an R (red) brightness value, a G (green) brightness value and a B (blue) brightness value. Furthermore, it is desirable that the three-dimensional image display displays a three-dimensional OSD (On Screen Display) which is a menu setting screen, and so on. Each pixel of the OSD has R, G and B brightness values, blend information indicative of a blend ratio between the image signal and the OSD, and depth information.
A circuit for generating the OSD and a circuit for superimposing the OSD on the image signal may be integrated on two different chips. In the three-dimensional display device, it is necessary to transmit not only the R, G and B brightness values and the blend information, but also depth information. Therefore, there is a problem that the transmission system may be complicated.